[irishsultan]

The table is about dependency checking for those constructs.

E.g. SELECT countries.code, countries.name, count(*) FROM countries JOIN countries_languages as co_lang on co_lang.country_code = countries.code GROUP BY countries.code

This isn't supported by Postgres, because countries.name is not in the group by clause, on the other hand it does make sense, because code will be unique in the countries table, so there will always be only one name for a given code.

(see https://mysqlserverteam.com/mysql-5-7-only_full_group_by-imp... which is also linked from the original article)

[kbenson]

And as specifically noted in that linked article you reference, it talks about how functional dependencies are a feature of SQL-99.

This aspect of the original article is really talking about how MySQL decided to implement a more up-to-date version of the spec that many competitors when they finally addresses their deficiency (as well they should, finally being SQL-92 compliant in the 2010's wouldn't really be anything to boast about).